For example, the above-described power unit as a driving source for an electric motor is mounted on an electric vehicle running by the electric motor or the like, a hybrid vehicle running with a combination of an engine and the electric motor, or the like. The power unit is composed of a battery assembly 1 (FIG. 1) and a battery connector 2 (FIG. 7) attached to the battery assembly 1. As shown in FIG. 1, the battery assembly 1 is composed of a plurality of batteries 10 arranged side-by-side relationship. A positive electrode 12 and a negative electrode 13 projected from a box-shaped chassis are provided with each battery 10. The positive electrodes 12 and the negative electrodes 13 are overlapped with each other in a manner that they are alternately arranged in the plurality of batteries 10.
As shown in FIG. 7, the battery connector 2 includes: a plurality of bus bars 3 for directly connecting the plurality of batteries 10 by connecting the positive electrode 12 and the negative electrode 13 of the batteries 10 adjacent to each other; a terminal 4 connected to each bus bar 3; an electric wire 5 connected to the terminal 4; a not-shown earth wire; and a synthetic-resin-made plate 6 receiving them.
A pair of bus bar holes 3a for respectively inserting the positive electrode 12 and the negative electrode 13 of the batteries 10 adjacent to each other is provided with the bus bar 3. When the positive electrode 12 mounted on one of the batteries 10 adjacent to each other is inserted into one of the pair of bus bar holes 3a, the bus bar 3 is attached to the positive electrode 12. When the negative electrode 13 mounted on the other one of the batteries 10 adjacent to each other is inserted into the other one of the pair of bus bar holes 3a, the bus bar 3 is attached to the negative electrode 13. By attaching in this manner, the bus bar 3 electrically connects the positive electrode 12 and the negative electrode 13 of the batteries 10 adjacent to each other.
The terminal 4 is composed of a bus bar connecting portion 41 and an electric wire connecting portion 42. A terminal hole 41a for inserting any one of the positive electrode 12 and the negative electrode is provided with the bus bar connecting portion 41. The bus bar connecting portion 41 is overlapped with the bus bar 3 while any one of the positive electrode 12 and the negative electrode 13 is inserted into the terminal hole 41a. An area of the bus bar connecting portion 41 is about half of the area of the bus bar 3. The electric wire connecting portion 42 is integrally provided with the bus bar connecting portion 41. The electric wire connecting portion 42 is composed of a pair of crimping pieces 100 with which a core wire of the electric wire 5 is crimped. The electric wire 5 is connected to a not-shown voltage measuring unit for measuring a voltage across each of the batteries 10.
A bus bar receiving portion 61, an electric wire receiving portion 62, an electric wire connecting portion receiving portion 63, and the like are integrally provided with the plate 6. The bus bar receiving portion 61 is formed in a box shape allowed to fit the bus bar 3 thereinto, and receives the bus bar 3 and the bus bar connecting portion 41 overlapped with the bus bar 3. A pair of not-shown plate holes for respectively inserting the positive electrode 12 and the negative electrode 13 is provided on a bottom wall of the bus bar receiving portion 61. The electric wire receiving portion 62 is formed in a gutter shape, and receives the electric wire 5. The electric wire connecting portion receiving portion 63 is formed in a gutter shape for communicating the bus bar receiving portion 61 with the electric wire receiving portion 62, and receives the electric wire connecting portion 42.
The power unit having the above-described structure is assembled as follows. When assembling the power unit, the bus bar 3, the terminal 4, the plate 6, and the like have been separately produced. Further, the electric wire 5 is previously connected to the terminal 4. Incidentally, a connection procedure of the terminal 4 and the electric wire 5 is done as follows. First, the core wire of the electric wire 5 is exposed by removing an insulating cover at an end of the electric wire 5. Then, the core wire is positioned between the pair of crimping pieces 100, and the pair of crimping pieces is crimped to pressure-bond the electric wire 5 to the electric wire connecting portion 42.
Next, the bus bar 3 is received in the bus bar receiving portion 61 of the plate 6 in a manner that the not-shown plate hole is overlapped with the bus bar hole 3a. Next, the bus bar connecting portion 41 is overlapped with the bus bar 3 and received in the bus bar receiving portion 61 in a manner that the terminal hole 41a is overlapped with one of the pair of bus bar holes 3a. At this time, the bus bar connecting portion 41 is overlapped with the bus bar 3 in a manner that the electric wire connecting portion 42 is received in the electric wire connecting portion receiving portion 63. Then, the electric wire 5 is arranged in the electric wire receiving portion 62.
Next, the battery connector 2 assembled according to the above described procedure is attached to the battery assembly 1. Namely, one positive electrode 12 of the batteries 10 adjacent to each other is inserted into one of the pair of not-shown plate holes and one of the pair of bus bar holes 3a overlapped with each other, and one negative electrode 13 of the batteries 10 is inserted into the other one of the pair of not-shown plate holes and the other one of the bus bar holes 3a. Further, the battery connector 2 is arranged on an upper wall of the battery assembly 1 in a manner that any one of the positive electrode 12 and the negative electrode 13 is inserted into the terminal hole 41a. Then, by respectively screwing nuts onto the negative electrode 13 and the positive electrode 12 of the batteries 10, the battery connector 2 is fixed to the batteries 10.